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Virtual monitoring added to MARIN’s portfolio of services


One of the core services of MARIN is to carry out measurement campaigns on board and to analyse the collected data. MARIN is now combining decades of developments in hydrostructural tools with online wave hindcast models to perform virtual monitoring.


Ingo Drummen & Remco Hageman, i.drummen@marin.nl


ntil now, MARIN usually performed monitoring using accurate sensors and a fully synchronised system. However, not all monitoring questions require the same accuracy. For instance, to quantify the performance of a numerical tool, a traditional, highly accurate system is required. On the other hand, when a global idea of the consumed fatigue budget is of concern, a more cost-effective measurement system with lower instantaneous accuracy could provide sufficient information. Currently, MARIN is developing a broader range of monitoring systems to more specifically serve the needs of our clients.


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VHSM Virtual hull structure monitoring (VHSM) takes advantage of the numerical methods developed over the last decades and combines these with online wave hindcast models. The accuracy of such a monitoring system is inherently lower when compared to a traditional system. But how much lower? It is also important to take into account that costs and the effort involved in setting up the system are also significantly lower.


Insight into the accuracy of VHSM systems is of vital importance for their success. The design of experiments and value of information are key aspects of the Valid 3 JIP that kicked-off in November last year. As part of the JIP, work is being done to investigate the accuracy of a VHSM system. For the project two USCG cutters, USCGC BERTHOLF and USCGC STRATTON were instrumented with a traditional hull structure monitoring system. These are a perfect platform for investigating the VHSM system’s accuracy. Investigations so far have focused on USCGC STRATTON. Results for one four-month deployment of the ship are shown in the figure. The blue reference line represents the cumulative fatigue damage derived from strain gauge measurements near one of the structural hot-spots.


The other two lines correspond to this same detail and give the results from the virtual hull monitoring approach. Given the limited availability of AIS data for this ship, the heading and speed information was derived from an installed GPS. The response amplitude operator of the stress at the


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